Harvesters such as cotton pickers and cotton strippers include upright cotton conveying ducts directing cotton from the harvesting structure upwardly and rearwardly into a telescoping basket or receptacle. One problem with such a fixed arrangement is lost productivity resulting from the need to stop the harvester to dump the cotton into a boll buggy, module builder or cotton trailer. Typically the basket must be raised for unloading, and the flow of cotton from the air system has to be stopped to avoid crop loss. Although accumulator systems such as shown in commonly assigned U.S. Pat. No. 6,263,650 have been built for use with on-board processors such as module builders or bailers to avoid interruptions in harvesting during unloading, the problem of lost productivity during basket unloading in off-machine processing systems still persists. Since off-machine processing and the infrastructure associated with such processing continues to dominate the cotton industry, an improved system is necessary to reduce or eliminate harvester down time during basket unloading.